fix(dashboard): unsqueeze kanban columns on tablet viewports

The 769–1024px breakpoint forced 6 columns into the visible width with
`grid-template-columns: repeat(6, minmax(0, 1fr))` and `overflow-x:
hidden`, collapsing columns to ~130–170px on Android tablets and
stacking task card titles one word per line. Switch to
`minmax(260px, 1fr)` with `overflow-x: auto` so columns keep a readable
minimum width and the board scrolls horizontally, matching desktop.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/styles.css

@@ -3190,9 +3190,12 @@ input[type="range"]:focus-visible {
 }
 
 @media (min-width: 769px) and (max-width: 1024px) {
+  /* Tablet: 6 columns at 1fr collapse to ~130–170px each, which makes
+     task cards stack one word per line. Use a real minimum column width
+     and let the board scroll horizontally instead. */
   .board {
-    grid-template-columns: repeat(6, minmax(0, 1fr));
-    overflow-x: hidden;
+    grid-template-columns: repeat(6, minmax(260px, 1fr));
+    overflow-x: auto;
   }
 }